Re: please DON'T run 2.5.27 with IDE!

[Jens Axboe <axboe@suse.de>]

On Wed, Jul 24 2002, Bartlomiej Zolnierkiewicz wrote:
> 
> On Wed, 24 Jul 2002, Jens Axboe wrote:
> 
> > On Wed, Jul 24 2002, Bartlomiej Zolnierkiewicz wrote:
> > > > void blk_start_queue(request_queue_t *q)
> > > > {
> > > >          if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) {
> > > >                  unsigned long flags;
> > > >
> > > > ================== possigle race here for qeue_flags BTW.
> > > >
> > > >                  spin_lock_irqsave(q->queue_lock, flags);
> > > >                  clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
> > > >
> > > >                  if (!elv_queue_empty(q))
> > > >                          q->request_fn(q);
> > > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > > If we call it from within request_fn then if this isn't recursion on the
> > > > kernel stack then I don't know...
> > >
> > > You really don't know.
> > >
> > > And funny thing is I have diffirent blk_start_queue() function in my tree
> > > (2.5.27) ? Without described above race and without possibilty of
> > > recursion...
> > >
> > > 2.5.27:drivers/block/ll_rw_blk.c
> > > void blk_start_queue(request_queue_t *q)
> > > {
> > >         if (test_and_clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) {
> > >                 unsigned long flags;
> > >
> > >                 spin_lock_irqsave(q->queue_lock, flags);
> > >                 if (!elv_queue_empty(q))
> > >                         q->request_fn(q);
> > >                 spin_unlock_irqrestore(q->queue_lock, flags);
> > >         }
> > > }
> >
> > Yep, the version Martin posted must be really old.
> 
> It's worst. Martin's version exists only in his tree (mind?).

:-)

> I checked back revision and blk_start_queue() was inroduced in 2.5.19
> and it was the correct one.

There were buggy versions at one point, however they may not have made it
into a full release. In that case it was just bk version of 2.5.19-pre
effectively. I forget the details :-)

-- 
Jens Axboe